Kindle does not yet allow you to set a default dictionary for Irish in the usual way.
Instructions on how to use this dictionary in pop-up mode are provided in the How do I use a Collins Kindle dictionary section.
If you have any issues with this, please contact dictionaries@harpercollins.co.uk
Compatibility & Functionality
(For technical help email: dictionaries@harpercollins.co.uk)
• Basic Text Search works on all Kindle devices
• Index lookup works on all Kindles except Kindle Fire and Kindle Fire HD
• Search across the full English to Irish dictionary by headword.
• Show Irish translations in a pop-up window when reading English books.